threat vs warning

threat and warning both are nouns.

Word	Noun	Adjective	Verb	Adverb
threat	Yes	No	No	No
warning	Yes	Yes	No	No

As nouns, warning is a hypernym of threat; that is, warning is a word with a broader meaning than threat:

threat (noun)	warning (noun)
a warning that something unpleasant is imminent	a message informing of danger
declaration of an intention or a determination to inflict harm on another	cautionary advice about something imminent (especially imminent danger or other unpleasantness)
a person who inspires fear or dread	notification of something, usually in advance
something that is a source of danger

threat (adjective)	warning (adjective)
	serving to warn